Method of treating armor-plate.



TATlilg OFFICE.

SA1V[UEL S. \VALES, F MUNHALL, PENNSYLVANIA, ASSIGNOR T0 CARNEGIE STEEL COMPANY, OF PITTSBURGH, PENNSYLVANIA, QJGORPORATION OF NEW JERSEY.

cpyers theback and all the edges of. the.

1,5 plate. leaving the face to be hardened exposed. The faceof the plate is exposed to the heat of the furnace, while the; other pap-ts ofthe plate are protected by theloam, an this? ,face is raised to about dat) de- .Q; gre'es to v950 degrees centigrade. During thislieating, the body of the plate hcated i by conductiomfrom the face to successively lesserdegrees from the face to the back, the back being usually about 550 degrees to 600 ,5 degreescentigrade. The plate is then re moved from the furnaceand .water sprays directed against bothfaees. This gives the final hardness to the face of the plate, and

. at;-t-he'same time, the. body of ,theplate is softened or annealed by reason otitstempe 'aturebeinginthe range in which water annealing takes place. The strength of the body of the plate is decreased by this treatment, and this can not be remedied, it being 3 the final treatment.

My invention is designed to overcome this difliculty and to provide a method which will give the same strength and resistance in the hardened face, while at'the same time,

40 retaining the original strength and toughness of the body.

-In carrying out my process, I may treat the plate in the ordinary manner up to the final water-hardening; that is, in the ordinary method, the ingot \Vlll be torgcd, carburized, rcforged and then tibered in the usual way. Of course, the plate may be re- :lorged or not as desired, as this is an optional step in the method. The plate is 'then placed in a furnace where the plate to bc hardened is exposed to the heat and the edges are preferably protected by loam in the usual manner. The lower face of the plate, however, is leftozfposed, and is positively cooled in any desired way. For this Specification or Letters Patent. Applipation filed Nbiremberll, 1507. Serial No. 401,702.

l-Ieretofore in IltI ETHOD OF TREATING ARMUR-PLATE Patented June 10,1913;

purpose, I preferably apply sprays of water, steam, air or other cooling fluid to the back. face of the plate. This positive cooling isv preferably continued tl1rough.thc teena er the face, and the face will thus become heatcthto, say, 850 degrees to 950 degrees centig adc, while the back of. the plate will be kept at any desired low temperature, preferably below 400 degrees und at most below 500 degrees centigrade. In practice, I have been able to keep the bucket the, plate as low as 300 degrees centigrade, while I attaining a temperature of 950 degrees centigrade on the face. The plate is then removed from the furnace and water; quemhcd in the usual manner, as, for ex-, ample by spraying both faces of the plate with theovaterf In this naiewquenching the heated face of the plate receives its final hardness, while the body of the plate is not materially changed in its cha -acteristics, on account of, having been maintainediat a much lower temperature than that of its final toughening treatment.

When the plate which has been heatedaccording to my method is withdrawn from the furnace,fit shows two zones, namely. the

zone which shows heat color extending from,

the heated :lace through almutfone-third: ofthe depth of the plate: and the second Zone 86 which extends through two-thirds of the face through the cooled back. and which shows substantially no color. There is, of. course, no sharp line of demarcation bctween the two zones, one zone merging into 90 the other. a

The results of my invention are that the body of the plate for one-half or more of its thickness retains the tough eharacteristics imparted'by the previoustoughening treatment, and these characteristics are not changed by the final water-hardening of the face, whereas in former practice, this portion of the plate was materially softened. In the former method of heating, the. differonce of temperature between the front and back of the plate depended wholly upon the time of heating and the character of the insulating medium, the loam acting merely as a passive insulation to prevent heating from the bottom and edges and compelling the heat to soak through from the face. There was no positive cooling. In my improved process, by positivcly cooling the back of the plate, 1 can control the temperature of the major portion of the body independent of and regardless of the amount of time usedin heating. Changes may be madev in the steps of treatment of the armor .plate prior to the final heating for water-hardening withoutdeparting from my invention.

In a modification of my method, the back of the plate being heated may be cooled by applying a thinner plate to it, and then positively cooling the back of this thinner plateby a water spray or other similar means. In thiscase, the cooling action will betransmitted to the plate proper by conduction rather than by direct action upon it, as in my preferred form. The second plate may be either in dircctcontact' with the mam plate, or material may be placed be tween themto modify or vary the influence of the cooling. 7

I claim: v 1. In the manufacture of, face-hardened armor plate, the step consisting of heating to a hardeningtemperature that face -of the plate which is to be hardenedand simultaneously maintaining the back face of the plate below 400 degrees centigrade by artificially' cooling the same; substantially as described. g V

2. In the manufacture of face-hardened armor plate, the step-*5 consisting of heating to a hardening temperature thatface of the.

plate which .is to be hardened while main-, tainingthe opposite face below a ,water annealing temperature by applying a cooling fluid thereto and then quenching the atescribed.

to harden its face; substantially -'de- 3. In the manufacture of armorplate, the

steps consisting in heating one face. of the plate to between 850 degrees to 950 degrees .centigrade, simultaneously maintaining another face of the plate below 400 degrees .centigrade and then quenching the plate;

substantially as described.

4:. In the manufacture of armor plate, the

steps consisting in covering and thereby protecting thefedges of a plate, applying heat to one face thereofand simultaneously and positively cooling the opposite face thereof by forcing a cooling liquid against it and' then quenching the plate; substantially as described. j j

' 5. In the-manufacture of armor plate the steps consisting in covering and thereby protecting the edges of the plate, applying -;heat to one face thereof, simultaneously and ositively cooling the oppositeface thereof y forcing a cooling liquidfa gainst' it and then quenching the plate; substantially as described.

'6. In the manufacture of armor plate, the

I steps consisting of forging the plate, carburizing one face thereof and then heating one face thereof to between 850 to 950 degrees Centigrade, simultaneously cooling the" red color is visible; substantially as de- In testimony .whereof, I- have hereunto set my hand. r

' S. S. WALES.

I Wit'nessesp.

R. D. 'Iirrrna. 

